In order to grow, reproduce and evolve life requires a supply of energy and nutrients. Astrobiology has the challenge of studying life on Earth in environments which are poorly characterized or extreme, usually both, and predicting the habitability of extraterrestrial environments. We have developed a general astrobiological model for assessing the energetic and nutrient availability of poorly characterized environments to predict their potential biological productivity. NutMEG (nutrients, maintenance, energy and growth) can be used to estimate how much biomass an environment could host, and how that life might affect the local chemistry. It requires only an overall catabolic reaction and some knowledge of the local environment to begin making estimations, with many more customizable parameters, such as microbial adaptation. In this study, the model was configured to replicate laboratory data on the growth of methanogens. It was used to predict the effect of temperature and energy/nutrient limitation on their microbial growth rates, total biomass levels, and total biosignature production in laboratory-like conditions to explore how it could be applied to astrobiological problems. As temperature rises from 280 to 330 K, NutMEG predicts exponential drops in final biomass (109−106 cells l−1) and total methane production (62−3 μM) despite an increase in peak growth rates (0.007−0.14 h−1) for a typical methanogen in ideal conditions. This is caused by the increasing cost of microbial maintenance diverting energy away from growth processes. Restricting energy and nutrients exacerbates this trend. With minimal assumptions NutMEG can reliably replicate microbial growth behaviour, but better understanding of the synthesis and maintenance costs life must overcome in different extremes is required to improve its results further. NutMEG can help us assess the theoretical habitability of extraterrestrial environments and predict potential biomass and biosignature production, for example on exoplanets using minimum input parameters to guide observations.

中文翻译：

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在天体生物学和极端条件下预测可居住性、生物量和生物特征的生物能模型

为了生长、繁殖和进化，生命需要能量和营养的供应。天体生物学面临的挑战是在特征不佳或极端的环境中研究地球上的生命，通常两者兼而有之，并预测外星环境的宜居性。我们开发了一个通用的天体生物学模型，用于评估特征不佳的环境的能量和营养可用性，以预测其潜在的生物生产力。NutMEG（养分、维持、能量和生长）可用于估计环境可以容纳多少生物量，以及这种生命可能如何影响当地的化学。它只需要整体分解代谢反应和当地环境的一些知识就可以开始进行估计，还有更多可定制的参数，例如微生物适应。在这项研究中，该模型被配置为复制关于产甲烷菌生长的实验室数据。它被用来预测温度和能量/养分限制对其微生物生长速率、总生物量水平和类似实验室条件下的总生物特征产生的影响，以探索如何将其应用于天体生物学问题。随着温度从 280 K 上升到 330 K，NutMEG 预测最终生物量（109-106 个细胞 l-1）和甲烷总产量（62-3 μM）呈指数下降，尽管峰值增长率（0.007-0.14 h-1）有所增加对于理想条件下的典型产甲烷菌。这是由于微生物维持将能量从生长过程中转移出来的成本增加造成的。限制能量和营养素会加剧这一趋势。假设 NutMEG 可以可靠地复制微生物生长行为，但需要更好地理解生命周期必须克服的不同极端情况下的综合和维护成本，才能进一步改善其结果。NutMEG 可以帮助我们评估外星环境的理论宜居性并预测潜在的生物量和生物特征的产生，例如在使用最小输入参数来指导观测的系外行星上。